Flexible couplings for transmitting torque between a driving and a driven shaft are known. See for example, U.S. Pat. No. 5,000,722 which is commonly assigned and the disclosure of which is incorporated herein by reference. Such diaphragm type couplings are typically employed to transmit torque from a drive to a driven shaft while absorbing and sometimes dissipating the effects of misalignment. In a number of applications, a flexible coupling is designed to operate under relatively steady state conditions in terms of the torque applied and transmitted.. However, in certain specific applications, it is necessary to assure continued operation of the coupling even though occasionally, abnormally nigh torque values are imposed on the coupling even over a short time span. It is practically not feasible or cost effective to design a conventional coupling that would satisfy both sets of conditions of high flexiblility and high torque capacity and yet operate satisfactorily in its normal operating state. For a flexible coupling, such as that disclosed in U.S. Pat. No. 5,000,722, undesirable compromises in the flexibility of the coupling would have to be imposed, which would result in a loss of flexibility which would itself tend to cause premature failure due to misalignment, or would result in undesirable, high magnitude reactor loads onto the connected equipment.